Writing instrument



FIG. 1 is a perspective view of the writing instrument showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a left side view thereof. 

The ornamental design for a writing instrument, as shown and described. 